High-strength, high-toughness SiCp reinforced Mg matrix composites manufactured by semisolid injection molding

Particle-reinforced Mg matrix composites possess excellent mechanical and physical properties. In this study, a new processing technique, semisolid injection molding, was employed to fabricate SiCp/AZ91D composites. The microstructure and mechanical properties of the as-molded composites were investigated. The SiC particles were found to be uniformly distributed in the metal matrix and no agglomeration was observed. The presence of small voids next to the SiC particles was observed. The microhardness of the composites decreases with the increase of SiC content, and initially decreases and then increases to a stable level with the increase of casting temperature. The 2.5 wt% SiCp/AZ91D composite has the highest tensile strength, up to 10% higher than AZ91D and 18% higher than the 1 wt% SiCp/AZ91D composite. A large number of small dimples and spherical voids, formed after unmelted Mg particles were pulled out of the matrix, were observed on the tensile fracture surface. This study demonstrates that semisolid injection molding is a valuable technique for the manufacture of particle-reinforced metal matrix composites.